Exam 2 - Welcome to Grossmont College

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Exam 2 - Welcome to Grossmont College Powered By Docstoc
					Grossmont College                                   Name _____________________________
Chemistry 115
Summer 2008                                         Date    _____________________________

                                              Exam 2

Part I: Multiple Choice (2 points each)
Directions: Please circle the best answer for each of the following questions.

Question 1.   Which of the following of                Question 6.     Predict the product for the
              Dalton’s proposals is still                              reaction:      ∆
              valid?                                                  Ca (s) + O2 (g) 
              a) atoms are indivisible.                                a) CaO2 (s)
              b) atoms are indestructible.                             b) Ca2O (s)
              c) all atoms of an element                               c) CaO (s)
                   are identical.                                      d) Ca2O3 (s)
              d) all of the above                                      e) not enough information
              e) none of the above
                                                       Question 7.    What type of chemical reaction
Question 2.   Which of the following is not                           is illustrated in question 6?
              true about the Bohr model of                            a) decomposition
              the atom?                                               b) single replacement
              a) Electrons are repelled by                            c) combustion
                   the nucleus.                                       d) double replacement
              b) Electrons further from the                           e) neutralization
                   nucleus have more energy.
              c) Works for simple one                  Question 8.    Which of the following pieces
                   electron systems                                   of laboratory glassware has a
              d) Electron orbits has a                                precision of ± 0.1?
                   quantized distance and                             a) 50 mL beaker
                   fixed energy                                       b) 250 Erlenmeyer flask
              e) none of the above                                    c) test tube
                                                                      d) 50 mL graduated cylinder
Question 3.   What      is   the   electron                           e) none of the above
              configuration of the iron(II)
              ion?                                     Question 9.    If you spill some chemical on
              a) [Ar] 3d6                                             your hand, you should
              b) [Ar] 4s23d4                                          a) rinse your hand in the sink
              c) 1s22s22p63s23p64s23d6                                     for fifteen minutes.
              d) 1s22s22p63s23p64s24p6                                b) rinse your hand in the
              e) [Ar] 4d6                                                  safety shower.
                                                                      c) wash your hand with soap
Question 4.   Classify potassium sulfate as                                and water.
              a) binary ionic                                         d) ignore it.
              b) ternary ionic                                        e) all of the above
              c) binary molecular
              d) ternary oxyacid                       Question 10.   Predict the energy sublevel
              e) hydrate                                              filled by elements scandium,
                                                                      Sc, through zinc, Zn.
Question 5.   What is the systematic name                             a) 4d
              for aqueous HCl?                                        b) 4f
              a) monohydrogen                                         c) 2d
                   monchloride                                        d) 4p
              b) hydrochloric acid                                    e) 3d
              c) hydrogen chloride
              d) chloric acid
              e) all of the above

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Grossmont College                                                               Chemistry 115
Vance                                                                           Summer 2008

Part II: Matching (1 point each)
Directions: Select the key term that corresponds to each of the following definitions.

a.   atomic mass            e   1. Atoms of the same element that have a different number of
b.   frequency                     neutrons
c.   ion
d.   isoelectronic          h   2. A region about the nucleus in which there is a high
e.   isotope                       probability of finding an electron with a given energy
f.   nucleus
g.   precipitate            d   3. Refers to ions or atoms having the same electron
h.   orbital                       configuration
i.   polyatomic ion
j.   single replacement     c   4. An atom that bears a charge as a result of gaining or losing
                                   valence electrons

                            i   5. A group of atoms bound together and having an overall
                                   positive or negative charge

                            f   6. A region in the center of an atom containing protons and

                            a    7. The average mass of all the naturally occurring isotopes of
                                    an element

                            g    8. An insoluble solid substance produced from a reaction in
                                    aqueous solution

                            b   9. The number of times a light wave completes a cycle in 1

                            j   10. A type of reaction in which a more active metal displaces a
                                    less active metal from solution

Part III: Short Answer
Directions: Answer each of the following questions. Be sure to use complete
sentences where appropriate. For full credit be sure to show all of your work.

Question 1.      Predict the melting point for tungsten metal, W, given the melting points
                 of chromium, Cr, is 1,857 °C and molybdenum, Mo, is 2,617 °C (4

                 Cr       1857 °C       difference 2617 °C – 1857 °C = 760 °C
                 Mo       2617 °C
                 W          ?           ? = 2617 °C + 760 °C = 3377 °C

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Grossmont College                                                             Chemistry 115
Vance                                                                         Summer 2008

Question 2.   Can ions of different elements have the same number of protons? Can
              ions of difference elements have the same number of electrons? Explain
              your reasoning (6 points).

              Ions of different elements cannot have the same number of protons
              because a change in the number of protons changes the identity of the
              element. Ions of different elements can have the same number of
              electrons. For example the oxide ion, O 2-, nitride ion, N3-, both have ten
              electrons total and are isoelectronic with a neon atom.

Question 3.   Complete the nomenclature table (18 points):

              Formula of Compound         Type of Compound            Name of Compound
                                       (ionic, molecular, acid)    (bonus for latin name, if
                       FeS                       Ionic                  Iron(II) sulfide or
                                                                          ferrous sulfide
                       SiO2                   Molecular                  Silicon dioxide

                     (NH4)2O                     Ionic                 Ammonium oxide

                    Al2 (CO3)3                   Ionic                Aluminum carbonate

                      CoCl3                      Ionic               Cobalt(III) chloride or
                                                                       cobaltic chloride
                      Br3O8                   Molecular              Tribromine octoxide
                      HCl (aq)                    Acid                 Hydrochloric acid

                      AgCN                       Ionic                   Silver cyanide

                     HNO2 (aq)                    Acid                     Nitrous acid

Question 4.   Name the element that corresponds to the following (10 points):

              a.     Which alkali metal has the most metallic character?              Fr

              b.     Which halogen has the smallest atomic radius?                    F

              c.     What group of elements has two valance electrons? Alkaline earth

              d.     Which noble gas has the highest ionization energy?               He

              e.     Has the electron configuration 1s22s22p63s23p64s23d5             Mn

                                      Page 3 of 4
Grossmont College                                                                    Chemistry 115
Vance                                                                                Summer 2008

Question 5.          Complete the following table (10 points):

       Atomic             Atomic      Mass         Number of Number of Number of
       Notation           Number      Number       Protons   Electrons Neutrons
              34   Se2-        34          78          34            36         44
         Xe-131                54         131           54         54           77
               50  Sn4+        50         120           50           46         70

Question 6.           Silver has two isotopes. Silver-107 has an atomic mass of 106.91 amu
                     and percent abundance of 51.84%. What is the atomic mass of silver-109
                     if it has a percent abundance of 48.16% (10 points)?

Question 7.          Below are some reactions, please balance and identify the type of reaction
                     that is taking place (8 points):

           a.             2 Al (s) + 3 MnSO4 (aq)  Al2(SO4)3 (aq) + 3 Mn (s)
                             single replacement reaction

           b.             2 LiNO3 (s) + heat  2 LiNO2 (s) +     O2 (g)
                             decomposition reaction

           c.             H2SO4 (aq) + 2 NH4OH (aq)  (NH4)2 SO4 (aq) + 2 H2O (l)
                            acid-base neutralization reaction
                            (special type of double displacement reaction)

           d.             4 Co (s) + 3 O2 (g)  2 Co2O3 (s)
                             combination or synthesis reaction

Question 8.          Write a balanced equation for the combustion of liquid ethyl alcohol,
                     C2H5OH, with oxygen gas to give carbon dioxide and water gases (4

                     C2H5OH (l) + 3 O2 (g)  2 CO2 (g) + 3 H2O (g)

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